TWI651112B - Plug connector - Google Patents

Abstract

The plug-in joint according to the present invention can suppress the occurrence of poor insertion during the connection operation. The plug-in joint according to the present invention includes: a receiving member (20 '), which is provided inside the receiving port (20a) in a manner capable of moving in and out in a radial direction There is an engagement claw (24 ') having an arc-shaped inner peripheral surface (24a') provided with an inclined surface portion (24a1 ') on the front end side, and an insert (10) at the insertion port (10a) A front end edge portion (11) having a cylindrical surface-shaped outer peripheral surface is provided on the outer periphery, and an outer peripheral step portion (12) is provided on the distal end side of the front end edge portion (11), wherein the inclined surface portion (24a1 ') has The area including the first contact position with the corner portion on the outer peripheral side of the front edge portion has a curvature on a virtual plane perpendicular to the axis of the receiving opening (20a), which is smaller than the small diameter side portion of the outer step portion (12) The curvature of 12a) is closer to the curvature of the large-diameter side portion (11a) of the outer step portion (12) than the small-diameter side portion (12a).

Description

Plug-in connector

The present invention relates to a plug-in joint, and more particularly to a connection structure of a plug-in joint suitable for use as a connector for fire fighting.

Generally, fire-fighting hoses are used to connect fire-fighting hoses, fire-fighting hoses and pipe guns, and fire hydrants and fire-fighting hoses. As shown in FIG. 9, the plug-in joint as one of the connecting members has a structure in which the insert 10 and the receiving member 20 can be detached. Here, the outer peripheral step portion 12 provided on the front end portion of the insert 10 and the engagement claw 24 provided on the receiver 20 are fitted and connected. A release member (push ring) 14 is attached to the insert 10, and the release member 14 is used to separate the engaging claw 24 of the receiver 20 from the outer peripheral step portion 12 of the insert 10. By pushing the release member 14 toward the receiver 20, the engaging claws 24 are retracted toward the outer peripheral side, so that the engaging claws 24 can be separated from the outer peripheral step portion 12. Thereby, the connection state between the inserter 10 and the receiver 20 is released, and the inserter 10 and the receiver 20 can be separated (for example, refer to the following patent document 1).

However, in the above-mentioned plug-in joint, a plurality of arc-shaped engaging claws 24 protrude in the receiving port 20a of the receiving member 20 under the action of a spring member (not shown). When inserting the insertion opening 10a of the insert 10 into the receiving opening 20a of the receiving member 20, the front end edge portion 11 of the insert 10 It comes into contact with the inclined surface portions 24a1 of the plurality of engaging claws 24, and enters the receiving opening 20a of the receiving member 20 while pressing the engaging claws 24 toward the outer peripheral side. Finally, when the engaging claw 24 is opposed to the outer peripheral step portion 12 of the insert 10, the engaging claw 24 is protruded again through the above-mentioned spring member to engage with the outer peripheral step portion 12.

[Prior Art Literature]

[Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2001-116150

However, in the conventional plug-in joint described above, when the inserting member 10 is inserted into the receiving member 20 obliquely during the connection operation of the joint, the inserting member 10 and the receiving member 20 may encounter each other and cannot be inserted. In addition, in this case, the inserting member 10 and the receiving member 20 may be engaged with each other and cannot be inserted and removed. Furthermore, there are cases in which although the insert 10 can be inserted into the receiving member 20, the installation feeling is poor, and the connection operation cannot be performed smoothly and comfortably, for example, it may be stuck in the middle of insertion, and the insertion direction may be changed and the force applied again. In order to connect the two and so on.

Therefore, the present invention has been made in order to solve the above problems, and an object thereof is to provide a connection structure capable of suppressing occurrence of a poor insertion during the connection operation of a plug-in connector.

In view of the above, the plug-in joint of the present invention includes a receiving member provided with an engaging claw inside the receiving port, wherein the engaging claw can move in and out in a radial direction of the receiving port, and is applied with a force. The engaging claw is protruded toward the inner peripheral side, and the engaging claw has An arc-shaped inner peripheral surface; and an insert provided with a front end edge portion having a cylindrical surface-shaped outer peripheral surface on an outer periphery of the insertion opening, and a distal end side of the front end edge portion is provided with the card A claw-engaged outer stepped portion; the plug-in joint is configured to be connected by engaging the claw with the outer stepped portion when the insertion port is inserted into the receiving port; The inclined surface portion has a region including a position in contact with a corner portion on the outer peripheral side of the front edge portion of the front end at the beginning of the connection operation. The curvature of the region on a virtual plane perpendicular to the axis of the receiving port is smaller than that of the region. The curvature of the small-diameter side portion of the outer stepped portion is closer to the curvature of the large-diameter side portion of the outer stepped portion than the small-diameter side portion. In addition, in this case, it is not limited to the case where the curvature on the virtual plane of the area has a value between the curvature of the small-diameter side portion and the curvature of the large-diameter side portion, and the area is also included. In the case where the curvature on the virtual plane is less than the curvature of the large-diameter side portion.

In the present invention, it is preferable that the curvature on the virtual plane of the region is equal to or less than the curvature of the large diameter side portion. It is particularly preferred that the curvature on the virtual plane of the region coincides with the curvature of the large-diameter side portion.

In the present invention, it is preferable that an inner peripheral edge portion adjacent to an inner edge of the inclined surface portion is provided on the inner peripheral surface; and the region includes from an outer edge or an outer boundary to the inner boundary of the inclined surface portion. The outer boundary is located at a position in a radial direction of the inclined surface portion corresponding to a corner portion on the outer peripheral side of the front edge portion when the receiving member is not connected and the engagement claw is in a protruding state. Between the surface part and the outer edge, the inner boundary is located between the surface part and the inner edge; in a range from the inner boundary to the inner edge, as the The curvature of the inner peripheral edge portion is at least a main body portion different from the inclined surface portion, and the curvature on the virtual plane of the inclined surface portion gradually changes from the curvature of the region to the curvature of the inner peripheral edge portion.

In the present invention, it is preferable that an inner peripheral edge portion of the inner peripheral surface of the engaging claw has a curvature greater than that of the large-diameter side portion in at least a main body portion other than the left and right end edge portions, and has The curvature below the curvature of the small-diameter side portion will be described. In this case, the curvature on the virtual plane of the region may be set to a value smaller than the curvature of at least the main body portion of the inner peripheral edge portion in place of the above condition. In this case, it is preferable that the curvature on the virtual plane of the region is closer to the curvature of the large-diameter side portion than the curvature of at least the main body portion of the inner peripheral edge portion. In addition, in this case, it is not limited to the case where the curvature on the virtual plane of the area has a value between the curvature of the small-diameter side portion and the curvature of the large-diameter side portion, and the area is also included. In the case where the curvature on the virtual plane has a value equal to or less than the curvature of the large-diameter side portion. In addition, it is preferable that the curvature of at least the main body portion of the inner peripheral edge portion has a value closer to the curvature of the small diameter side portion than the large diameter side portion.

In the present invention, it is preferable that the ridge line portions on both sides of the inner peripheral surface (the inclined surface portion and the inner peripheral edge portion) in the circumferential direction have a rounded shape with a radius of 0.3 mm or more, or an inverted shape with a width of 1.0 mm or more. Angular shape. In this case, it is preferable that the ridge line portion has a rounded shape with a radius of 0.5 mm or more, or a chamfered shape with a width of 1.0 mm or more. In addition, it is preferable that left and right end edge portions having curvatures closer to the curvature of the large-diameter side portion of the outer stepped portion than the curvature of the main body portion are provided on the inner peripheral edge portion. It is preferable that the curvature of the end edge portion coincides with the curvature of the large-diameter side portion.

In the present invention, it is preferable that the engaging claw is formed of a sintered part, a forged part, or a cast part formed by compression molding. Here, it is preferable that the engagement claw is made of a sintered metal. In addition, it is preferable that the engaging claws include an inner peripheral wall constituting the inner peripheral surface, an engaging wall constituting an engaging surface engaged with the outer peripheral stepped portion, and an inner peripheral wall and an inner peripheral surface, respectively. The side walls of the side surfaces on both sides in the circumferential direction where the engaging surfaces intersect have a box-shaped structure integrally formed. In this case, the inside of the box structure and the back of the inner peripheral wall On the side, it is more effective to provide a reinforcing rib structure integrally connected to the inner peripheral wall and the engaging wall. Preferably, a part of the reinforcing rib structure is connected to a spring member that applies a biasing force toward the inner peripheral side of the engaging claw.

According to the present invention, the inclined surface portion of the engaging claw has a region having a curvature smaller than that of the small-diameter side portion of the outer peripheral step portion and close to the curvature of the large-diameter side portion, or an area having The area of curvature makes it difficult to apply a circumferential force to the engaging claws in the initial stage of the connection operation, and the guidance function of the inclined surface that abuts the front edge of the insertion port is improved. This can suppress the connection operation of the plug-in joint. The excellent effect is that a poor insertion occurs and the connection operation can be performed smoothly. In addition, since the matching degree between the corners on the outer peripheral side of the front edge of the insertion port and the inclined surface portion is closer to the surface contact state, the impact applied to the engaging claws and the front-end edge portion in the initial connection operation can be reduced, and the number of cards can be reduced. Damage to the claw or the insertion opening, and durability improvement.

1‧‧‧Plug-in connector

10‧‧‧ Insert

10a‧‧‧Inlet

11‧‧‧ front edge

11p‧‧‧ Corner on the outer side

11a‧‧‧large diameter side

12‧‧‧ Outer Step

12a‧‧‧Side side section

13‧‧‧Connection Department

14‧‧‧Release part

14a‧‧‧Cylinder

14b‧‧‧ flange

20, 20’‧‧‧ Accepted

20a‧‧‧Receiving mouth

21‧‧‧ front edge

22‧‧‧ Subject

22a‧‧‧Connection Department

22b‧‧‧Mounting frame

23‧‧‧ Fastening ring

23a‧‧‧Mount

24, 24’‧‧‧ engaging claws

24a 、 24a’‧‧‧ 内 内 面

24a1, 24a1’‧‧‧ inclined face

o‧‧‧ outer edge

o’‧‧‧ outside boundary

i‧‧‧ inner edge

i’‧‧‧ inside border

24a2‧‧‧‧Inner peripheral edge

24a2’‧‧‧ the main part of the inner peripheral edge

24a3 ’‧‧‧ the end edge portion of the inner peripheral edge portion

24b, 24b’‧‧‧ engagement surface

24c, 24c’‧‧‧ side

24d, 24d’‧‧‧ abutment department

24e‧‧‧Frame

24f‧‧‧outer surface

24g, 24g’‧‧‧ boss

Ba‧‧‧Inner peripheral wall

Bb‧‧‧ snap wall

Bc, Bd, Be‧‧‧ side wall

Ca ~ Cc‧‧‧ reinforced rib structure

25‧‧‧Spring Parts

26‧‧‧Claw seat

26a‧‧‧ opening

27‧‧‧Protection parts

J1, J2‧‧‧ridgeline

Ra, Rb, Rc‧‧‧curvature radius

s, s ’, s’’‧‧‧ surface position

g, g’‧‧‧ clearance

te, tf, tg, tg’‧‧‧ contact

FIG. 1 is a diagram showing an example of a shape of an engagement claw of a plug-in joint according to this embodiment, in which (a) is an internal view showing a state when viewed from an axis side of a receiving port, and (b) is an axis direction Front view of the state at the time of observation, (c) is a rear view showing the state at the time of observation along the axis direction, (d) is a cross-sectional view showing the cross section taken along the line DD in (b), and (e) is a display A cross-sectional view of the cross-section taken along line EE in (b).

FIG. 2 (a) is a cross-sectional view showing a cross section of the engagement claw of the present embodiment taken along line AA in (c), (b) is an external view of the engagement claw of the present embodiment, (c) It is a side view which shows the circumferential direction side surface of the engagement claw of this embodiment.

FIG. 3 is a longitudinal cross-sectional view showing a state in an initial stage of a coupling operation according to the present embodiment.

FIG. 4 is a longitudinal sectional view showing a state at an intermediate stage of a coupling operation according to the present embodiment.

FIG. 5 is a vertical cross-sectional view showing a state in a completion stage of a coupling operation according to the present embodiment.

(A) and (b) in FIG. 6 are enlarged views showing the relationship between the existing structure and the insertion opening and the engagement claw in the present embodiment in the initial stage of the connection operation, respectively.

(A) and (b) in FIG. 7 are enlarged views showing the relationship between the existing structure and the insertion opening and the engagement claw in the present embodiment in the middle stage of the connection operation, respectively.

(A) and (b) of FIG. 8 are enlarged views showing the relationship between the existing structure and the insertion opening and the engagement claw in the present embodiment in the completion stage of the connection operation, respectively.

FIG. 9 is an exploded perspective view of an insert and a receiving member of a plug-in joint of a conventional structure.

(A) is an internal view which shows the engagement claw of a conventional structure, (b) is a front view of an engagement claw, (c) is a side view of an engagement claw.

Next, embodiments of the present invention will be described in detail with reference to the drawings. First, a basic structure of a conventional plug-in connector will be described with reference to FIG. 9. It should be noted that both the conventional structure and the basic structure of the present embodiment in the following description are described in Japanese Industrial Standards (JIS) B9911-1968 "Dimensions of Plug-in Connectors for Fire Hose".

As shown in FIG. 9, a conventional plug-in joint includes an insert 10 and a receiver 20, and these two components are respectively connected to various components or equipment such as a fire hose, a pipe gun, a fire hydrant device, and a fire automobile. The insert 10 is formed in a cylindrical shape as a whole. The insert 10 has an insertion opening 10 a at a front end portion in the axial direction. A front end edge portion 11 is provided on an opening edge side of the insertion opening 10a of the front end portion, and the front end edge portion 11 has an outer peripheral surface portion (large diameter side portion) having a larger diameter. In addition, a small-diameter outer peripheral surface portion (small-diameter-side portion) is formed on the distal end side of the front-end edge portion 11, and an outer peripheral step portion 12 is formed between the large-diameter-side portion and the small-diameter-side portion.

In addition, the axial end portion of the insert 10 is provided with a connection portion 13 corresponding to various instruments. In the case of the example shown in the figure, this connecting portion 13 is a mounting portion of a fire hose. Further, an annular release member (pushing wheel) 14 is fitted on the outer peripheral surface of the intermediate portion in the axial direction of the insert 10 so as to be movable in the axial direction. The release member 14 includes a cylindrical body portion 14 a having a cylindrical shape and an annular flange portion 14 b. The cylindrical body portion 14 a is slidably mounted on an outer peripheral surface of a middle portion of the insert 10. 14b protrudes from the distal end side of this cylindrical part 14a toward the radial direction outer side.

On the other hand, the receiver 20 is also connected to the same various devices as described above. The receiver 20 is also formed in a cylindrical shape as a whole, but the front end edge portion 21 corresponding to the receiving port 20a in the axial direction front end portion has a shape that expands outward in the radial direction compared to the axial end portion. The receiver 20 has a connecting portion 22a corresponding to various appliances or equipment on the distal side, and a receiver body 22 having a cylindrical shape on the front end side, and the receiver body 22 has a mounting frame portion 22b having an enlarged diameter. A fastening ring 23 is attached to the attachment frame portion 22b of the receiver body 22 from the front end side by screwing or the like. A plurality of engaging claws 24 are mounted on the inner side of the fastening ring 23 in a state of being biased toward the inner diameter side by a spring member such as a leaf spring, and the engaging claws 24 are freely accessible to the opening portion of the claw base 26. The ring-shaped mounting seat 23a provided on the outer periphery of the fastening ring 23 is attached with a flexible material. A cylindrical protective member (also referred to as a "rubber band", a "tire", etc.) 27 formed of an elastic raw material.

When the insertion port 10a of the insert 10 is inserted into the receiving port 20a of the receiving member 20, the front edge portion 11 abuts against the engaging claw 24. Next, the insert 10 is further pushed, and the front edge portion 11 moves toward the inside in the axial direction with the engaging claws 24 being squeezed toward the outer peripheral side. When the outer peripheral step portion 12 moves beyond the engaging claws 24 and moves inward, the engaging claws 24 is reset by the spring force of the spring member, and engages with the outer peripheral step portion 12. As a result, the inserting member 10 and the receiving member 20 are connected and cannot fall off.

On the other hand, in a state where the insert 10 and the receiving member 20 are connected, the release member (push ring) 14 is pushed toward the receiving port 20a side with the finger in contact with the flange portion 14b, etc., so that the front edge of the cylindrical portion 14a It comes into contact with the engagement claw 24 and presses the engagement claw 24 toward the outer peripheral side. Therefore, the engagement state between the engagement claw 24 and the outer peripheral step portion 12, that is, the connection state between the insert 10 and the receiver 20 is released. Accordingly, when a separating force is applied in the axial direction, the insert 10 and the receiver 20 can be separated.

(A)-(c) of FIG. 10 shows the approximate shape of the conventional engagement claw 24. As shown in FIG. Among them, (a) in FIG. 10 is an internal view showing a state when the engaging claw 24 is viewed from the inner peripheral side of the receiving member 20 toward the outside in the radial direction, and (b) is an engaging view when the engaging member 20 is viewed from the front end side in the axial direction of the receiving member 20. (C) A front view of the claw 24 when viewed from the circumferential direction.

The engagement claw 24 includes an inner peripheral surface 24a facing the inner peripheral side of the receiver 20, and a distal end side of the inner peripheral surface 24a across the ridge line (Figures (a) and (c) in FIG. 10 The upper side is shown) adjacent engagement surfaces 24b, and left and right side surfaces 24c adjacent to both sides of the inner peripheral surface 24a in the circumferential direction via a ridge line. It should be noted that the circumferential direction included in this specification refers to a direction that rotates around the axis of the receiving port 20a. In addition, The peripheral surface 24a, the engaging surface 24b, and the left and right side surfaces 24c are provided on the outer peripheral side (the lower sides shown in (b) and (c) in FIG. 10), and abutments are held inside (outer peripheral side) of the claw seat 26 Department 24d. The base portion 24d is provided with a frame portion 24e, an outer peripheral surface 24f, and a boss 24g. The frame portion 24e is formed on both sides in the axial direction of the base portion 24d, and the outer peripheral surface 24f is formed inside the frame portion 24e. In the shape of an arc, a boss 24g is protrudingly provided at a central position of the outer peripheral surface 24f, and is riveted and fixed in a state of penetrating the spring member.

The inner peripheral surface 24a has an inclined surface portion 24a1 and an inner peripheral edge portion 24a2 inside the receiving port 20a. The inclined surface portion 24a1 extends obliquely from the outer edge o located on the outer peripheral side of the front end toward the inner edge i located on the inner peripheral side of the distal end. The inner peripheral edge The portion 24a2 is adjacent to the inner edge i of the inclined surface portion 24a1 via a ridge line. Each of the inclined surface portion 24a1 and the inner peripheral edge portion 24a2 is formed in a concave arc shape extending in the circumferential direction inside the receiving port 20a. In addition, the inclined surface portion 24a1 has a surface having a convex curved surface profile along a direction from the outer edge o toward the inner edge i. On the other hand, the width of the inner peripheral edge portion 24a2 is in accordance with the "claw" dimension t ₂ prescribed by JIS. An arc-shaped concave curved surface formed under the conditions of 2.0 mm (when the nominal diameter is 65 mm). The curvature of the inner peripheral edge portion 24a2 is defined in JIS as the radius of curvature Ra = D / 2 = 32.25 mm (when the nominal diameter is 65 mm). The inner peripheral edge portion 24a2 is formed in a flat shape when viewed from the axial direction.

JIS has stipulated the size of each part of the engaging claw 24. For example, the length l _{1 of the} inner circumferential surface 24 a in the tangential direction around the axis is 36 mm (when the nominal diameter is 65 mm), and the length l _{2 of the} base portion 24 d in the tangential direction of the axis is 42 mm (when the nominal diameter is 65 mm). However, the curvature on the imaginary plane perpendicular to the axis of the inclined surface portion 24a1 is not specified. However, since the engaging claw 24 is usually formed by cutting or the like, it is formed with the same curvature as the inner peripheral edge portion 24a2 due to manufacturing constraints. The material of the engaging claw 24 is usually a copper alloy such as CAC403.

Next, the structures of the insert and the receiver of the plug-in joint of this embodiment will be described with reference to FIGS. 1 to 8. In addition, in this embodiment, the structure of the inserting member 10 may be completely the same as the above-mentioned conventional structure, and the structure of the receiving member 20 'other than the engaging claw 24' may be the same as that of the receiving member 20 described above. Therefore, in this embodiment, the description of the same parts as the above-mentioned conventional structure is omitted. In addition, since this embodiment is set to the size prescribed | regulated by JIS like the said conventional structure, description about the conventional structure or the structure prescribed | regulated by JIS is also abbreviate | omitted.

Here, (a) in FIG. 1 is an internal view showing the engaging claw 24 ', (b) is a front view when the engaging claw 24' is viewed from the front end side in the axial direction of the receiver 20 ', and (c) is (D) is a cross-sectional view showing a cross section taken along line DD in (b), and (e) is a view taken along (b) A cross-sectional view of the section after the middle EE line is cut. In addition, (a) in FIG. 2 is a cross-sectional view showing a cross-section taken along the line AA in (c), (b) is an external view showing the engaging claw 24 ', and (c) is a card viewed from a circumferential direction. Side view of the claw 24 '.

The engaging claw 24 'is configured such that the curvature on at least one of the inclined surface portions 24a1' of the inner peripheral surface 24a 'on a virtual plane perpendicular to the axis is as follows. That is, for example, the curvature radius Rb = d1 / 2 = 34.25 mm (when the nominal diameter is 65 mm). Among them, d1 is the size of the "insert" specified by JIS, and d1 = 68.5mm (when the nominal diameter is 65mm). In the present embodiment, as described above, the inclined surface portion 24a1 'is provided with a region having the same curvature on the virtual plane as the outer peripheral surface of the outer diameter d1 of the front end edge portion 11 of the insert 10. This area includes the entire range of the inclined surface portion 24a1 'from the outer edge o to the inner edge i. The radius that first contacts the corner portion of the outer peripheral side of the front end edge portion 11 of the insertion opening of the insert 10 at the initial stage of the later-mentioned connection operation. Position in the direction. Usually, the above-mentioned area is an area from the outer boundary o 'to the inner boundary i. However, in the example shown in the figure, the above-mentioned region is a range up to the boundary between the inner peripheral edge portion of the inner peripheral surface 24a 'of the engagement claw 24', that is, the inner edge i. Therefore, the inner boundary i 'is indicated by a dotted line. here, The inner peripheral edge portion of the inner peripheral surface 24a 'of the engagement claw 24' includes a main body portion 24a2 'and left and right end edge portions 24a3'.

On the other hand, the curvature on the above-mentioned virtual plane of at least the main body portion 24a2 'of the inner peripheral edge portion except for the left and right end edge portions 24a3' is the same as the conventional technology. The curvature radius Ra = D / 2 = 32.25 (mm when nominal diameter is 65mm). Among them, D is the size of the "claw" prescribed by JIS, D = 64.5mm (when the nominal diameter is 65mm). In the illustrated example, the curvature on the virtual plane at the outer edge o of the inclined surface portion 24a1 'has a curvature radius Rc = S / 2 = 36.7 mm (when the nominal diameter is 65 mm). Among them, the inner diameter dimension S = 73.4mm (when the nominal diameter is 65mm) is the size of the "claw" specified by JIS D = 64.5mm (when the nominal diameter is 65mm) and the size of the "claw" d specified by JIS = 82.0mm (when nominal diameter is 65mm) (preferably intermediate value).

Here, in the illustrated example, the curvature of the main body portion 24a2 'of the inner peripheral edge portion is close to the curvature of the small-diameter side portion 12a of the outer peripheral step portion 12, as described above, but the left and right end edge portions 24a3' of the inner peripheral edge portion. The curvature of is preferably closer to the curvature of the large-diameter side portion 11a of the outer step portion 12 than the curvature of the main body portion 24a2 '. In the case of the illustrated example, the curvature of the left and right end edge portions 24a3 'has a curvature radius of d / 2 = 34.25mm and d = 68.5mm (when the nominal diameter is 65mm), that is, the curvature with respect to the above-mentioned large-diameter side portion 11a. Same curvature. In this case, among the inner edges i of the inclined surface portion 24a1 ', the portions of the inner edge i located at the boundary between the left and right end edge portions 24a3' of the inner peripheral edge portion and the inclined surface portion 24a1 'are located on both sides of the surface. The curvature on the virtual plane is the same. However, the inclination angles of the surfaces located on both sides of the inner edge i portion in a direction parallel to the axis direction are different from each other (the difference is whether they are inclined with respect to the axis).

In the inclined surface portion 24a1 ', the curvature from the outer edge o to the outer boundary o' of the rising portion gradually decreases, and the curvature on the outer boundary o 'has a radius of curvature Rb = d ₁ /2=34.25 mm (nominal diameter is At 65mm). Further, in the example shown in the figure, in the region between the outer boundary o ′ and the inner edge i, the inclined surface portion 24a1 ′ has the following Rb = d ₁ /2=34.25 mm (when the nominal diameter is 65 mm). Fixed curvature. Here, the left and right end edge portions 24a3 'are not provided in the portion between the inclined surface portion 24a1' and the main body portion 24a2 'of the inner peripheral edge portion, or as a shape different from the example shown in the figure. In this case, the inner edge i becomes a boundary line having different curvatures on the virtual plane. However, in the above part or in the above case, the range of the area having the curvature may be set to the inner boundary i ′ indicated by the dotted line in the figure at a position closer to the outer boundary o ′ than the inner edge i. until. In this case, the curvature on the virtual plane of the portion between the inner boundary i 'and the inner edge i may be gradually changed in such a manner that the curvature gradually increases from the curvature in the above region, and finally the inner edge i The point becomes consistent with the curvature of the inner peripheral edge portion. This makes it possible to make the insertion operation smooth and stable when transitioning from the initial stage to the intermediate stage of the connecting operation described later.

In addition, the above-mentioned area may be a range including the above-mentioned surface portion of the inclined surface portion 24a1 ', that is, the surface portion that first comes into contact with the corner portion 11p on the outer peripheral side of the front-end edge portion 11 or the front-end edge at the beginning of the connection operation. The surface portion corresponding to the radial position of the corner portion 11 p on the outer peripheral side of the portion 11. For example, the region may include at least a range from the outer boundary o 'to the inner boundary i'. At this time, the range from the outer edge o to the outer boundary o 'and the range from the inner boundary i' to the inner edge i are arbitrary ranges. Of course, the above-mentioned region may be set to a range from the outer edge o to the inner boundary i ', a range from the outer edge o to the inner edge i, or a range from the outer boundary o' to the inner edge i.

In addition, in general, the curvature on the virtual plane of the region does not have to be fixed as described above. In addition, the curvature on the virtual plane of the region may be smaller than the curvature of the small-diameter side portion 12a of the outer peripheral step portion 12 and closer to the curvature of the large-diameter side portion 11a than the curvature of the small-diameter side portion 12a. In this case, it is preferable that the curvature on the virtual plane of the above-mentioned region is at the large-diameter side portion 11a. Below the curvature. Here, the curvature on the virtual plane of the above-mentioned region may be consistent with the curvature of the large-diameter side portion 11a.

Alternatively, the curvature on the virtual plane of the region may be smaller than the curvature of the main body portion 24a2 'of the inner peripheral edge portion. In this case, it is preferable that the curvature on the virtual plane of the above-mentioned area is closer to the curvature of the large-diameter side portion 11a than the curvature of the main body portion 24a2 'of the inner peripheral edge portion. In this case, it is also preferable that the curvature on the virtual plane in the region is equal to or less than the curvature of the large-diameter side portion 11a.

In addition, the engaging claw 24 'is provided with edge edges such as a ridgeline portion J1 and a ridgeline portion J2. The ridgeline portion J1 is located between the inclined surface portion 24a1' and the side surface 24c 'and the ridgeline portion J2 is located inwardly. Between the left and right end edge portions 24a3 'of the peripheral edge portion and the side surface 24c'. In the conventional structure, the above-mentioned edge corners generally have a chamfered shape with a width of about 0.1 mm to 0.2 mm, or a rounded shape with a radius of about 0.1 mm to 0.2 mm. However, in this embodiment, the ridge lines J1 and J2 have a rounded shape with a radius of 0.3 mm or a chamfered shape with a width of 0.5 mm. However, the ridgeline portions J1 and J2 may be provided with a rounded shape having a radius greater than 0.3 mm, for example, a radius of 0.5 mm or more (for example, a radius of 0.8 mm). A chamfered shape having a width of 1.0 mm or more (for example, a width of 1.5 mm) may be provided in the ridge line portions J1 and J2. This makes it possible to reduce the radial height of the engaging claws 24 'on the outer peripheral surface of the front end edge portion 11 at the initial stage and the intermediate stage of the coupling operation. Therefore, it is possible to achieve the effect of ensuring the stroke margin for the in / out operation of the engagement claw 24 '. In addition, by smoothing the shape of the corners of the ridgeline portions J1 and J2 as described above, the main effect according to the present invention, that is, the effect of suppressing the stress of the engaging claws 24 'in the circumferential direction can be further enhanced.

In addition, as shown in FIG. 1, the surface of the left and right end edge portions 24 a 3 ′ adjacent to the left and right ridgeline portions J2 is set to have a smaller curvature than the small-diameter side portion 12 a (or the main portion 24 a 2 ′ of the inner peripheral edge portion). For example, when a curvature such as a curvature radius Rb = d ₁ /2=34.25 mm (when the nominal diameter is 65 mm) or a curvature close thereto, the following effects can be obtained. That is, it is possible to further reduce the height in the radial direction of the engaging claws 24 ′ on the outer peripheral surface of the front edge portion 11 in the intermediate stage of the connecting operation described later. Accordingly, the stroke allowance in the radial direction of the engagement claw 24 ′ in the intermediate stage of the coupling operation can be further increased. In addition, since it can be brought into a surface contact state or close to a surface contact state with the outer peripheral surface, it is possible to reduce damage to the contact portion between the two and improve durability.

As shown in (e) in FIG. 1 and (a) and (b) in FIG. 2, the engagement claw 24 ′ of the present embodiment includes an inner peripheral wall Ba forming the inner peripheral surface 24 a ′ and a ridge line therebetween. The engagement wall Bb is adjacent to the inner peripheral wall Ba and forms the engagement surface 24b ', and the right and left side walls Bc adjacent to both the inner peripheral wall Ba and the engagement wall Bb and form the side surface 24c'. In addition, the base portion 24d 'is provided with a side wall Bd and a side wall Be. The side wall Bd extends from the inner peripheral wall Ba via the ridge portion (outer edge o), and the side wall Be is along the engagement wall. Bb extended form. Further, the engaging claw 24 'has a box-like structure in which the inner peripheral wall Ba, the engaging wall Bb and the side wall Be, the side wall Bd, and the left and right side walls Bc are integrally formed, and the inner The back surface side of the peripheral surface 24a 'is open.

An integrally formed rib structure is provided inside the box-shaped structure so as to be connected to the inner side surface of the inner peripheral wall Ba, and to connect the side wall Bd, the engagement wall Bb, and the side wall Be. Ca, Cb, Cc. In addition, a structure for connecting the spring member 25 (a boss in the example shown in the figure) 24g 'is protrudingly provided on the bottom of the central rib structure Ca. In addition, as long as the rib structures Ca, Cb, and Cc are formed integrally with at least the inner peripheral wall Ba and the engagement wall Bb, the strength and durability at the time of connection operation can be improved.

The engaging claw 24 'of the present embodiment is composed of sintered parts (specifically, metal sintered parts obtained by sintering with metal powder) made of various powders. As the metal, stainless steel such as SUS630 and SUS304 can be used. The sintered part can be formed by compression-molding a metal powder together with a binder and sintering it at a high temperature. In this case, a metal powder injection molding method can be used in addition to a normal powder metallurgy technique (press molding method). In addition, the engaging claw 24 'may be a cast part formed using a casting method such as a die-casting method or a forged part formed using a forging method such as a cold forging method. Although it is not a sintered part, it is similar to the above-mentioned method in terms of compression molding. the same.

The advantages of the above-mentioned manufacturing method are that it is easier to form a special surface shape (especially the surface shape of the inner peripheral surface 24a 'of the engaging claw 24' according to the present invention) than when performing a cutting process and the like, and This eliminates the need for cutting costs and reduces raw material costs. In addition, in the present embodiment, the inclined surface portion 24a1 'is provided with an area having a curvature smaller than that of the main body portion 24a2' or the small-diameter side portion 12a of the inner peripheral edge portion, so that the front edge portion 11 is easily connected to the inner portion at the beginning of the connection operation. The peripheral surface 24a 'contacts over a wide range in the circumferential direction. Therefore, even if the thickness of the inner peripheral wall Ba and the like of the engaging claw 24 'is reduced, damage to the inner peripheral surface 24a' of the engaging claw 24 'and the distal edge portion 11 can be reduced, and durability can be improved. Therefore, the cost of raw materials such as metal powder can be further reduced. In addition, the weight of the engaging claw 24 'can be reduced.

3 to 5 are cross-sectional views showing respective states of an initial stage, an intermediate stage, and a completion stage of a connection operation of the plug-in joint according to the present embodiment. In addition, (a) and (b) in FIGS. 6 to 8 are enlarged views showing the relationship between the conventional structure and the engagement claw of the present embodiment and the front end portion of the insertion port 10a in the above-mentioned stages, respectively.

First, the initial stage of the connection operation will be described with reference to FIGS. 3 and 6. As shown in Fig. 3, the insertion opening of the inserting member 10 is inserted into the receiving opening of the receiving member 20 '. At this time, the corner portion 11p on the outer peripheral side of the front end edge portion 11 of the insert 10 is in contact with the inclined surface portion 24a1 'of the engaging claw 24', so that the engaging claw 24 'faces in the direction of entering the opening 26a of the claw base 26 ( (Peripheral side). In addition, the said area includes the part of the inclined surface part 24a1 'which the corner part 11p of the outer peripheral side of the front-end edge part 11 contacts first. The above-mentioned region has at least a range between an outer boundary o ′ and an inner boundary i ′. The outer boundary o ′ is located on the inclined surface portion 24a1 corresponding to the radial position of the corner portion 11p on the outer peripheral side of the front edge portion 11. The surface portion 'is closer to the outer edge o side, and the inner boundary i' is located closer to the inner edge i side than the surface portion.

At this time, in the conventional structure, as shown in (a) of FIG. 6, the curvature of the above-mentioned area of the inclined surface portion 24 a 1 of the inner peripheral surface 24 a on the virtual plane perpendicular to the axis of the receiving port 20 a is larger than the front edge portion 11. The curvature of the outer surface. Therefore, a gap g is generated at the center portion in the circumferential direction between the surface position s on the above-mentioned virtual plane of the inclined surface portion 24a1 and the corner portion 11p on the outer peripheral side of the leading edge portion 11. Therefore, the corner portion 11 p on the outer peripheral side of the front-end edge portion 11 comes into contact with only the left and right ridge line portions of the inclined surface portion 24 a 1, thereby generating a point-shaped contact portion te. However, the figure shows a state where the insertion port 10a is inserted into the center position of the receiving port 20a, and the axis of the insertion port 10a and the receiving port 20a coincide. However, in practice, the insertion port 10 may be inserted at a position eccentric to the receiving port 20a, or the axis of the insertion port 10a may be slightly inclined with respect to the axis of the receiving port 20a. Therefore, the corner portion 11 p on the outer peripheral side of the front end edge portion 11 abuts only one of the left and right ridgeline portions of one engagement claw 24 to generate a contact portion te, thereby causing the engagement claw 24 to receive in the circumferential direction. As a result, the movement of the engaging claw 24 relative to the opening 26 a of the claw base 26 is not smooth enough.

For example, when three engagement claws 24 are arranged in the circumferential direction as shown in the example, in the conventional structure, the corner portion 11 p of the front-end edge portion 11 is restricted by six contact points in the circumferential direction. but, If the insertion port 10a is slightly eccentric or inclined with respect to the axis of the receiving port 20a, the engaging claw 24 receives a great force at a certain contact point and is not stressed at other contact points. In addition, since the position of the contact point of the force is located on the ridge portion (contact portion te) at the circumferential end of each engaging claw 24, the engaging claw 24 is easier than the component force in the radial direction. A component in the circumferential direction is generated. Accordingly, it is difficult to smoothly perform the operation of pressing the engaging claw 24 into the opening 26 a of the claw seat 26 with the corner portion 11 p. Therefore, it is difficult to insert the insertion port 10 a into the receiving port 20 a at the initial stage of the connection operation, and it is easy In the event of a collision or jam.

On the other hand, in this embodiment, as shown in FIG. 6 (b), the curvature on the virtual plane of the above-mentioned area of the inclined surface portion 24a1 'of the inner peripheral surface 24a' and the curvature of the outer peripheral surface of the leading edge portion 11 Consistent. Therefore, it is difficult for the gap g to occur in the entire circumferential direction between the surface position s 'on the virtual plane of the inclined surface portion 24a1' and the corner portion 11p on the outer peripheral side of the leading edge portion 11. Therefore, in the above-mentioned area of the inclined surface portion 24a1 ', the corner portion 11p on the outer peripheral side of the front-end edge portion 11 is in a state of being in line contact with or close to the entire area ta on the virtual plane. Therefore, even if the eccentric position is inserted at an early stage of the joining operation or the insertion is performed in an inclined posture as described above, since the inclined surface portion 24a1 'has a large curvature, it is easy to uniformly insert it at positions other than the circumferential end portion. The contact position of the corner portion 11p of the mouth 10a. Therefore, the force applied to the engaging claw 24 'is not easily deflected in the circumferential direction, but is easily directed outward in the radial direction. Therefore, it is easy to maintain the smoothness of the movement of the engaging claw 24' with respect to the opening 26a of the claw base 26.

Generally, the curvature of the above-mentioned region of the inclined surface 24a1 'of the engaging claw 24' which first comes into contact with the corner portion 11p at the initial stage of the connecting operation on a virtual plane perpendicular to the axis is smaller than that of the small-diameter side portion 12a, The curvature of the large-diameter side portion 11a is closer to that of the small-diameter side portion 12a. Alternatively, the curvature of the above-mentioned region on a virtual plane perpendicular to the axis is smaller than the curvature of at least the main body portion 24a2 'of the inner peripheral edge portion. because Therefore, the contact state between the corner portion 11p of the front end edge portion 11 and the engagement claw 24 'is closer to the line contact state than the point contact state, and the component force of the engagement claw 24' from the corner portion 11p in the circumferential direction is smaller than the conventional In accordance with this structure, the component force in the radial direction increases. Therefore, the engaging claw 24 'can enter the opening 26a of the claw seat 26 more easily than the conventional structure, and therefore, the insertion port 10a can be smoothly inserted into the receiving port 20a in the initial stage of the connection operation.

In addition, as the insertion opening 10a is gradually inserted into the receiving opening 20a as described above, the inclined surface portion 24a1 'of the engaging claw 24' guides the corner portion 11p on the outer peripheral side of the front edge portion 11 of the insertion opening 10a, thereby allowing the insertion The eccentric position or tilt posture of the mouth 10a is corrected. At this time, in the conventional structure, as described above, only the left and right ridgeline portions in the circumferential direction of each of the engagement claws 24 are contacted by the point-shaped contact portions te, so the guidance function is limited. On the other hand, in this embodiment, since the curvature of the inclined surface portion 24a1 'of the engagement claw 24' is large, the corner portion p can be guided in the entire circumferential direction. Therefore, in the initial stage of the connection operation, the insertion port 10a can be smoothly corrected to a position and angle that can be connected to the receiving port 20a. Therefore, it is possible not only to prevent a state where it cannot be inserted or a state where it cannot be pulled out due to a collision, but also to obtain a smooth installation feeling when transitioning from the initial stage to the intermediate stage during the connection operation.

Here, when the curvature on the virtual plane of the region is larger than the curvature of the large-diameter side portion 11a, it is preferable to increase the radius of the rounded shape of the ridgeline portion J1 or the ridgeline portion J1 as described later. The width of the chamfered shape. Thereby, the radial height of the engaging claw 24 'at the corner portion 11p on the outer peripheral side of the front end edge portion 11 can be slightly reduced, and the gap g can be reduced. Therefore, it is possible to slightly increase the radial stroke margin of the engaging claw 24 'in the initial stage, and thus it is possible to suppress the occurrence of poor connection such as occlusion due to the eccentric position or the inclined posture. In addition, it is possible to reduce the insertion resistance during the initial connection operation.

In addition, the present invention is not limited to this embodiment, as long as the curvature on the virtual plane of the region is lower than the curvature of the large-diameter-side portion 12a below the curvature of the large-diameter-side portion 12a, in addition, It is sufficient that the curvature is smaller than the curvature of at least the main body portion 24a2 'of the inner peripheral edge portion. At this time, the curvature on the virtual plane of the region may be smaller than the curvature of the large-diameter side portion 11a (curvature having a larger radius of curvature Rb). In this case, as shown by the two-dot chain line in (b) of FIG. 6, the curvature of the surface position s ″ on the virtual plane of the inclined surface portion 24 a 1 ′ is smaller than the curvature of the corner portion 11 p on the outer peripheral side of the leading edge portion 11. . Therefore, the corner portion 11p does not easily come into contact with the left and right end edge portions of the above-mentioned region of the inclined surface portion 24a1 'of the engagement claw 24', but easily comes into contact with the central portion of the above-mentioned region. Therefore, the component force in the circumferential direction received by the engaging claw 24 'becomes smaller, and the component force in the radial direction becomes larger. Therefore, it is possible to further suppress an obstacle to the movement of the engaging claw 24'.

In a state in which the eccentric position or inclined posture of the insertion port 10a with respect to the receiving port 20a is corrected to some extent in the initial stage described above, the insertion port 10a is further inserted into the receiving port 20a. Then, as shown in FIG. 4, the main body portion 24 a 2 ′ and the left and right end edge portions 24 a 3 ′ that become the inner peripheral edge portion of the engaging claw 24 ′ are moved to the outer peripheral surface (ie, the large-diameter side portion 11 a) of the front end edge portion 11. Status (intermediate stage). In this state, as shown in FIG. 7, in the conventional structure and the present embodiment, the inner peripheral edge portion (at least the main body portions 24 a 2 and 24 a 2 ′) having a large curvature is disposed on the outer periphery of the front edge portion 11 having a small curvature. Surface. As a result, only the left and right ridgeline portions J2 of the inner peripheral edge portion are brought into contact with the outer peripheral surface of the distal end edge portion 11 at the contact portions tf, tg.

At this time, in this embodiment, the radius of the rounded shape or the width of the chamfered shape of the left and right ridge line portions J2 may be increased like the main body portion 24a2 'of the inner peripheral edge portion (see FIGS. 7 and 8). Accordingly, by changing the contact portion tg between the ridgeline portion J2 and the outer peripheral surface of the front end edge portion 11, the radial height of the outer peripheral surface of the front end edge portion 11 of the engaging claw 24 'can be slightly reduced, so that the height can be reduced. Gap g '. therefore, Since the stroke allowance in the radial direction of the engagement claw 24 'in the intermediate stage can be slightly increased, it is also possible to suppress the occurrence of poor connection such as occlusion due to the inclined posture. In addition, it is also possible to reduce the insertion resistance during the connection operation in the intermediate stage. Further, as shown in FIG. 1, the curvature of the left and right end edge portions 24a3 'inside the ridgeline portion J2 may be partially reduced. That is, as described above, by providing the end edge portion 24a3 'having a curvature smaller than that of the main body portion 24a2' at the inner peripheral edge portion, the contact portion is enlarged as shown in tg 'in the figure, so that the left and right ridgeline portions J2 and J2 The contact state of the vicinity portion with the outer peripheral surface of the front-end edge portion 11 changed from a line contact state to a surface contact state. Therefore, in addition to the effects described above, it is possible to reduce the damage to the peripheral surfaces of the engaging claw 24 'and the insertion port 10a, thereby improving the durability.

Finally, when the insertion port 10a is further inserted into the receiving port 20a from the above intermediate stage, the leading edge portion 11 moves closer to the main body portion 24a2 'and the left and right end edge portions 24a3' of the inner peripheral edge portion of the engaging claw 24 '. At the inner position, the main portion 24 a 2 ′ of the inner peripheral edge portion and the left and right end edge portions 24 a 3 ′ are opposed to the small-diameter side portion 12 a of the outer peripheral step portion 12. Thereby, the engagement claw 24 'protrudes by the elastic force of the spring member 25, so that the engagement surface 24b' of the engagement claw 24 'engages with the outer peripheral step portion 12 and becomes a coupled state (completion stage).

As described above, in this embodiment, the curvature of a predetermined area of the inclined surface portion 24a1 'of the inner peripheral surface 24a' of the engagement claw 24 'is smaller than the existing curvature (that is, the radius of curvature Ra is greater than D / 2 = 32.25mm (nominal When the diameter is 65mm)). Therefore, in the initial stage of the coupling operation, the force applied to the engaging claw 24 'is not easily applied to the circumferential direction. Therefore, it is possible to prevent the engagement claw 24 'from being jammed in the opening 26a of the claw base 26' and being unable to operate, so that the engagement claw 24 'can be smoothly moved in and out. In addition, in the initial stage of the connecting operation, the corner portion 11p on the outer peripheral side of the insertion port 10a and the inclined surface portion 24a1 'of the engagement claw 24' are closer to the line contact state than the point contact state in the conventional structure. Therefore, the guiding function of the engaging claw 24 'for the insertion port 10a is improved, and the insertion port 10a can be smoothly corrected relative to the receiving port. 20a's eccentric position or tilt attitude. Therefore, it is possible to obtain a smooth and smooth installation feeling during the connection operation. Therefore, it is possible to suppress a defective insertion during the connection operation of the plug-in connector, and to perform the connection operation smoothly. In addition, the degree of matching between the corner portion 11p on the outer peripheral side of the front end edge portion 11 of the insertion port 10a and the inclined surface portion 24a1 'of the engagement claw 24' is close to the state of line contact, so that the initial application of the connection operation to the engagement claw 24 can be reduced 'And the impact on the front edge portion 11. Therefore, it is possible to reduce the damage of the engaging claw 24 'or the insertion port 10a and improve the durability.

In addition, the plug-in connector of the present invention is not limited to the configuration described in the above embodiment, and includes various forms based on the gist of the present invention. For example, in the above-mentioned embodiment, although the example which comprises the fire-fighting connector prescribed | regulated by JIS was shown, this invention is not limited to this. For example, as long as it is a joint provided with an insertion port and an engagement claw capable of performing the coupling operation as described above, it can be applied to any application. In addition, it is not limited to the size prescribed by JIS. Furthermore, the specific structure of the engagement claw is not limited to the above-mentioned illustrated example, and it is sufficient if it has an inner peripheral surface including an inclined surface portion and an inner peripheral edge portion, and an engaging surface capable of engaging with an outer peripheral step portion. Furthermore, in the above-described embodiment, the curvature of the inner peripheral edge portion may be almost constant over the entire range from the center to the left and right ridgeline portions J2 in the same manner as the conventional configuration.

Claims (12)

A plug-in joint includes: a receiving member, the receiving member is provided with an engaging claw inside the receiving port, the engaging claw can move in and out in a radial direction of the receiving port, and is applied by a force; And the engagement claw has a circular arc-shaped inner peripheral surface provided with an inclined surface portion on a front end side thereof, and an insert provided with a cylindrical surface on an outer periphery of the insertion port. A front edge portion of the outer peripheral surface, and an outer peripheral step portion capable of engaging with the engaging claw is provided on a distal side of the front edge portion; and the plug-in joint is configured to be inserted through the insertion port. When the receiving mouth is engaged, the engaging claws are engaged with the outer peripheral stepped portion, and the plug-in joint is characterized in that the inclined surface portion includes an outer periphery that is first included with the front edge portion at the beginning of the connecting operation. The area where the corner portion of the side touches, the curvature of the area on a virtual plane perpendicular to the axis of the receiving opening is smaller than the curvature of the small-diameter side portion of the outer stepped portion, and is smaller than the small-diameter side Partially connected The curvature of said large-diameter portion of the outer periphery of the stepped portion. The plug-in joint according to claim 1, wherein a curvature on the virtual plane of the region is less than a curvature of the large-diameter side portion. The plug-in joint according to claim 2, wherein the curvature on the virtual plane of the region is consistent with the curvature of the large-diameter side portion. The plug-in joint according to any one of claims 1 to 3, wherein an inner peripheral edge portion adjacent to an inner edge of the inclined surface portion is provided on the inner peripheral surface, and the region includes a portion from the inclined surface. The range from the outer edge of the face or the outer boundary to the inner boundary, wherein the outer boundary is located between the inclined face and the front edge portion when the receiving member is not connected and the engagement claw is in a protruding state. Between the surface portion at the radial direction position corresponding to the corner portion on the outer peripheral side and the outer edge, the inner boundary is located between the surface portion and the inner edge; from the inner boundary to the inner edge Within the range up to the edge, the curvature on the virtual plane of the inclined face portion gradually changes from the curvature of the area to at least the main body portion whose curvature toward the inner peripheral edge portion is different from the inclined face portion. The curvature of the inner peripheral edge portion will be described. The plug-in joint according to any one of claims 1 to 3, wherein an arc-shaped inner peripheral edge adjacent to a distal end side of the inclined surface portion and parallel to the axis is provided on the inner peripheral surface. The inner peripheral edge portion has a curvature greater than the curvature of the large-diameter side portion and equal to or less than the curvature of the small-diameter side portion in at least a main body portion other than the left and right end edge portions. A plug-in joint includes: a receiving member, the receiving member is provided with an engaging claw inside the receiving port, the engaging claw can move in and out in a radial direction of the receiving port, and is applied by a force; The engaging claw has a state of protruding toward the inner peripheral side, and the engaging claw has an arc-shaped inner peripheral surface, the inner peripheral surface is provided with an inclined surface portion at a front end side, and has an inner periphery adjacent to a distal end side of the inclined surface portion. An edge portion; and an insert provided with a front end edge portion having a cylindrical surface-shaped outer peripheral surface on an outer periphery of the insertion opening, and an end portion of the front end edge portion provided with the engaging claw The outer stepped portion that is engaged; the plug-in joint is configured to be connected by engaging the engagement claw with the outer stepped portion when the insertion port is inserted into the receiving port; The inner peripheral edge portion has a curvature greater than that of the large-diameter side portion of the outer peripheral step portion in at least a main body portion other than the left and right end edge portions, and a curvature of the small-diameter side portion of the outer step portion. The following curvature The inclined surface has a region including a position that first contacts the corner portion on the outer peripheral side of the front edge portion at the beginning of the connection operation, and the curvature of the region on a virtual plane perpendicular to the axis of the receiving port is smaller than the inner portion. The curvature of at least the main body portion of the peripheral edge portion. The plug-in joint according to claim 6, wherein the curvature on the virtual plane of the region is closer to that of the large-diameter side portion than the curvature of at least the main body portion of the inner peripheral edge portion. Curvature. The plug-in joint according to claim 6 or 7, wherein the region includes a range from an outer edge or an outer boundary of the inclined surface to an inner boundary, wherein the outer boundary is located between the inclined surface When the receiving member is not connected and the engaging claw is in a protruding state, a surface portion at a position in a radial direction corresponding to a corner portion on the outer peripheral side of the front end edge portion and the outer edge, the inner boundary Located between the surface portion and the inner edge; within a range from the inner boundary to the inner edge, as at least the main body portion toward the inner peripheral edge portion, the The curvature on the virtual plane gradually changes from the curvature of the region to the curvature of the inner peripheral edge portion. The plug-in joint according to claim 6 or 7, wherein the inner peripheral edge portion is provided with left and right end edge portions whose curvature is closer to the curvature of the large diameter side portion than the curvature of the main body portion. The plug-in joint according to any one of claims 1 to 3, 6, and 7, wherein the engaging claw is formed of a sintered part, a forged part, or a cast part formed by compression molding. The plug-in joint according to claim 10, wherein the engaging claws include an inner peripheral wall constituting the inner peripheral surface, an engaging wall constituting an engaging surface engaged with the outer peripheral stepped portion, and each constituted by The side wall of the side surface of the both sides of the circumferential direction which cross | intersects the said inner peripheral surface and the said engaging surface has a box-shaped structure integrally. The plug-in joint according to claim 11, wherein a reinforcing rib integrally connected to the inner peripheral wall and the engaging wall is provided inside the box structure and on the back side of the inner peripheral wall. structure.